[identity] Add function to query device by ID

Summary:
Added function that queries devices index to find device only by its ID.
Finds userID needed for full primary key, then calls existing function that does the rest.
It is used in D12304

Depends on D12348

Test Plan: Tested in D12304

Reviewers: varun, will, marcin

Reviewed By: varun

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12349